Integrated air spring

ABSTRACT

An air spring ( 10 ) for use in a motor vehicle suspension system is provided. The air spring includes a generally cylindrical flexible bladder ( 12 ) having a circular upper opening ( 18 ), a support unit ( 14 ) sealingly connected to the flexible bladder ( 12 ), and a unitary integrated top assembly ( 16 ) connected to the upper opening ( 18 ) in an air-tight manner. The support unit ( 14 ) further includes an installation fastener ( 52 ) for connection to a vehicle support brackets ( 78 ). The top assembly ( 16 ) includes a sealed body ( 34 ) having an interior open volume ( 23 ) and optional attachment components positioned on the body to connect the top assembly to a vehicle main frame. The top assembly further includes an optional connection port ( 28 ) adapted for pneumatic intercommunication with other air springs and an optional fill port ( 48 ) for connection to a pressurized air system.

FIELD OF THE INVENTION

[0001] The present invention relates to spring devices having a flexiblewall, and more particularly, to pneumatic spring devices with flexiblerubber walls for use in land vehicles as energy absorbing means.

BACKGROUND OF THE INVENTION

[0002] Pneumatic springs, commonly referred to as air springs, have beenused for motor vehicles for a number of years to provide cushioningbetween moveable parts in the vehicle. Air springs absorb shock loadsimpressed on the vehicle axles by the wheels striking an object in theroad or falling into a depression. An air spring typically consists of aflexible rubber sleeve, also called a bellows or a bladder. The sleevecontains a supply of compressed fluid and has one or more pistonslocated therein or thereunder. An end cap closes off the upper region ofthe sleeve. During use, the piston moves axially toward and away fromthe end cap so as to alternatingly compress and expand the volume withinthe sleeve. In this manner, the air spring acts as an energy absorbingmeans for the vehicle.

[0003] In known air spring arrangements, there are a numerous componentsattached to the end cap. One set of components is used to fill andrefill fluid pressure within the sleeve. Another set is used to attachthe air spring to the vehicle frame; another set is used to regulatefluid pressure between air springs. Such systems are effective, but aredifficult to assemble and maintain due to their numerous parts. Thus, aneed exists for an improved vehicle air spring that is easier toassemble and maintain, preferably by having fewer parts. The presentinvention is directed to fulfilling these needs and others, as describedbelow.

SUMMARY OF THE INVENTION

[0004] In accordance with aspects of the present invention, an airspring is provided for use in a motor vehicle. The air spring includes aflexible air bladder, a support unit connected to lower portions of thebladder, and a unitary integrated top assembly connected to upperportions of the bladder. The top assembly includes a lateral shelf, asealed body having an interior open volume and various attachmentcomponents positioned on the body for use in connecting the top assemblyto the main frame. The top assembly is connected to the bladder in anairtight manner so as to accommodate a pressure within the air spring.

[0005] In accordance with other aspects of the invention, an optionalconnection port may be provided in the top assembly body for pneumaticcommunication with other air springs. In one embodiment, the topassembly body is formed in the shape of a half cone with a curvedsurface and an upright surface and a connection port is formed as arigid arm extending outward from the body upright surface. In addition,an optional fill port may be provided in the top assembly to connectwith a ride height system. During use, the ride height system uses thefill port to regulate the air pressure within the air springs to adjustto applied loads.

[0006] In accordance with further aspects of the invention, the topassembly body optionally includes a number of internal support ribs. Inone embodiment, the internal support ribs are upright walls orientedfront to back and in parallel relation to one another. Such internalsupport structures aide in the transmission of external loads to themounting surface. In one embodiment, the unitary integrated top of theair spring is formed to increase the internal volume of compressiblefluid in addition to the bladder volume, and to maintain an internalpressure in the range between, but not limited to, about 15 psi to about150 psi. In another embodiment, the internal pressure is equal to orgreater than 150 psi.

[0007] In accordance with still other aspects of the invention, the topassembly is formed from an injection molded plastic. Alternatively, thetop assembly may be formed from a metal casting or by other unitarymeans.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The foregoing aspects and many of the attendant advantages ofthis invention will become more readily appreciated as the same becomebetter understood by reference to the following detailed description,when taken in conjunction with the accompanying drawings, wherein:

[0009]FIG. 1 is a perspective view of one embodiment of an integratedair spring formed in accordance with the present invention;

[0010]FIG. 2 is a side view of the air spring of FIG. 1;

[0011]FIG. 3 is front view of the air spring of FIG. 1;

[0012]FIG. 4 is a top down view of the air spring of FIG. 1;

[0013]FIG. 5 is a cross-sectional side view taken along line 5-5 in FIG.4;

[0014]FIG. 6 is a bottom up perspective view of another embodiment of anintegrated air spring in which internal ribs are provided in the topassembly; and

[0015]FIG. 7 is a perspective view of the air spring of FIG. 1 installedin a vehicle suspension system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] The present invention is an integrated air spring for use in amotor vehicle having a suspension system, a pressurized air supplysource, and various air system control components (i.e., levelingvalves, etc . . . ). The air spring includes a top assembly thatintegrates a number of components into a single piece. The single-piecetop assembly improves the structural and functional characteristics of apassive air spring during use. In addition, when the top assembly isformed as a single piece, the present invention is easier to assemble,maintain, and manufacture than known air springs.

[0017] Referring to FIGS. 1 and 5, the air spring 10 includes a flexiblebladder 12, a support unit 14, and an integrated top assembly 16. Theflexible bladder 12 is conventionally formed, with a generallycylindrical shape. The bladder includes a circular upper opening 18 andmay include a circular lower opening 20, such as the one shown. The topassembly is connected to the upper opening of the bladder in anair-tight manner, such as by bead clamping as shown in FIG. 5, or otherconventional means. The bladder is formed of known bladder materials,e.g., rubber, reinforced rubber, rubber compounds, etc.

[0018] Referring to FIG. 1, the top assembly 16 is preferably a unitarycomponent formed from injection molded plastic or from a thin wallcasting (e.g., using ferrous materials, aluminum, magnesium, etc.) Thetop assembly 16 includes a lateral lower shelf 22, a body 24, attachmentcomponents, and a pneumatic connection port 28. In the embodiment ofFIG. 1, the body is shaped similar to a half cone, where the cone hasbeen divided vertically and so includes an upright surface 32 and acurved surface 34. The smaller end of the half cone is located above thelarger, lower end of the half cone. Referring to FIG. 4, the lateralshelf 22 extends from the lower end of the cone to form a half circlehaving a radius similar to the radius of the half cone lower end.

[0019] Referring to FIGS. 5 and 6, the lateral shelf 22 does not extendcompletely across the body. Instead, the body includes an open interiorvolume 23 that is in pneumatic communication with the interior of theflexible bladder. The interior of the body optionally includes a numberof support ribs 36. If ribs are included, as shown in FIG. 6, they maybe molded in with the top assembly, spaced equally between sides, and/ororiented generally front to back. The ribs provide internal support forthe top assembly during use. Alternatively, the ribs may emanate from acentral location in the upright surface and fan out to connect to theinterior of the conical body walls. As a further alternative, the ribsmay be formed in a grid pattern. Ribs are optional and do not have tospan the interior volume. The use of support ribs should be consideredif the top assembly is to be made from plastic or composite materials.

[0020] The top assembly may be made in other shapes. The precise shapeshould allow for an internal volume and for any structural interiorsupport, if needed. The final shape will also be affected bymanufacturing considerations as well as installation considerations onthe chassis. Depending on the space available for installation, the ribshape, location and pattern may need to be minimized to ensure a maximuminternal volume, minimize affect on external aesthetics, and minimizesecondary operations.

[0021] The top assembly interior volume acts to reduce the spring rateand natural frequency of the air spring. Spring rate is inverselyproportionate to the internal volume and natural frequency varies withthe square of the spring stiffness. Thus, the top assembly improves theoverall performance of the air spring, which in turn, improves ridecharacteristics of the vehicle. Under-damped conditions should beconsidered during design and tuning of a particular air spring for aspecific application.

[0022] The attachment components shown in the embodiment of FIGS. 1 and4 are a pair of side moldings 38, 38′ formed in the top assembly body.The side moldings appear as a pair of lateral arms positioned on thecurved surface 34 at a midelevation. Each side molding includes alongitudinal hole 40, 40′ to receive a mounting bolt or screw. Thelateral arms and holes are used to connect the air springs to thevehicle's main frame longitudinal members 70 as described below. Theholes may be threaded or bare, and as known to those with skill in theart may require the use of a sleeve to ensure proper installation. Theholes 40, 40′ are not pneumatically connected to the interior of thebody in order to preserve the sealed, pressurized, nature of the volume23. As will be appreciated, other attachment and fastening arrangementsmay be used, depending on the space, size, and loading requirements of aparticular application. If a plastic is used to form the top assembly, ametal sleeve should be used within the holes.

[0023] The connection port 28 is pneumatically connected with other airsprings of the motor vehicle suspension system and is available toshuffle air between the air springs. This improves the load distributionbetween springs during vehicle use. This interconnection is provided byvarious air-hoses (not shown) connected between air springs. As bestshown in FIG. 5, the connection port 28 is formed as a rigid cylindricalmounting base 42 having an internal passage 44. The base 42 isintegrally formed with the body 16 and extends outward from the bodyupright surface 32 near the body upper end. A variety of connections,such as a formed nipple 46, are available to interface with the variousair hose parts. The base 42 may also include a fill port 48 connectableto a vehicle pressurized air supply source (such as compressor system)via leveling components. The internal passage 44 and fill port 48 areshown with a large diameter for clarity. In practice, the internalpassage diameter is sized to optimize communication between air springsduring operation.

[0024] The fill port is used to inflate and deflate the air spring aswell as regulate the air pressure in the air spring thereby maintainingvehicle ride height. The fill port function is optional and not requiredfor service, the exchange of air to and from the upper body beingdependent on the design requirements of the particular application. Aconventional height control valve (not shown) allows air to enter intoor out of the bladder. Ride height control systems are known in the artand generally activate in relation to applied loads.

[0025] Referring to FIGS. 3 and 5, the support unit 14 includes a piston50, an installation fastener 52, and an optional bumper 54. The piston50 is conventionally formed and connected to the bladder in an air-tightmanner, e.g., by use of an attachment plate 56 at the lower opening 20as shown in the embodiment of FIG. 5, where the bladder is attached toplate 56 which rests on the piston. The installation fastener 52 isrotatably connected through the piston 50 and the attachment plate 56via small holes formed in each. The fastener 52 includes a proximal end58 and a distal end 60. The fastener is positioned with the distal end60 extending from the lower surface of the piston 50. The proximal end58 is disposed within the interior of the bladder 12. The bumper 54 ispositioned about the proximal end 58 and is preferably rotatablyattached thereto. The bumper 54 is utilized and sized to contact theunderside of the top assembly and enhance the air-spring performanceduring rough road conditions. The bumper 54 is formed of a conventionalbumper material, such as, rubber, rubber compounds, plastic, etc.

[0026] Referring to FIG. 7, and as is conventional in motor vehicles,the vehicle includes a main frame having parallel longitudinal members70 interconnected by one or more cross members 72. Vehicle wheel axles74 are generally connected to and/or located within transmissionassembly 76. The vehicle wheels (not shown) are connected to the axleends. A support bracket 78 is attached to the transmission assembly 76near each wheel. The support brackets 78 are longitudinally andlaterally oriented and include holes to movably connect with the airspring installation fasteners 52. The longitudinal members 70 aresupported by the air springs 10. During use, the air springs 10 act tocushion the movement between the wheel axles 74 at the transmissionassembly 76 and the main frame 70.

[0027] As installed, the installation fastener 52 of the presentinvention air spring inserts into the opening formed in a supportbracket 78. The shelf 22 of the top assembly 16 is positioned below andadapted to support the vehicle main frames 70. As shown in FIG. 7, thetop assembly body 16 is disposed along the frame outer side surfaces.Holes 80 in the main frames are available to receive the mounting base42 of the pneumatic connection port 28 of the top assembly 16.Additional holes 82 are available to fasten the top assembly to theframe via the holes 40, 40′ in the side moldings 38, 38′.

[0028] During use, the vertical motion of the wheels is transmitted tothe support bracket 78 and in turn transmitted to the air spring piston50. The piston 50 pushes into the bladder 12 causing energy to beabsorbed by pressurization of air in the bladder. Air is replenished inthe air spring 10 by a pressurized air supply source in the vehicle, viathe air spring fill port 48. A typical air supply source is compressedair at 120 psi from a truck compressor system. Air distribution piping(not shown) is used to regulate air pressure between air springs byconnecting between the ports 28. This advantageously equalizes pressureamongst air springs and improves their overall wear characteristics. Inone embodiment, the air spring is formed to withstand operating airpressures in the range of about 15 psi to about 150 psi. Instances of 5psi have also been found to work.

[0029] As will be appreciated from a reading of the above, the presentinvention air spring provides a number of benefits, including theability to use a volume of air to lower the natural frequency of thesuspension system and adjust the spring rate or stiffness to anacceptable design level. The present invention top assembly can be usedto enhance the performance characteristics of other types of springdevices having a flexible wall as well.

[0030] Further, the present invention integrated air spring requiresfewer parts to manufacture, resulting in easier manufacture andmaintenance. In addition, by locating the attachment components in thetop assembly and extending the base through the main frame, thedistribution and air shuffling piping may be consolidated into fewerparts. The present invention integrates external piping and fittings,moves these connections to the vertical wall of the longitudinal framemembers and improves air spring vertical load characteristics outboardof the frame.

[0031] While the preferred embodiment of the invention has beenillustrated and described, it will be appreciated that various changescan be made therein without departing from the spirit and scope of theinvention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. An air spring for use ina motor vehicle having a main frame, a suspension system, and apressurized air supply source, the air spring comprising: (a) agenerally cylindrical flexible bladder having an upper opening; (b) asupport unit sealingly connected to the flexible bladder, the supportunit further including an installation fastener adapted to connect theair spring to the vehicle suspension system; and (c) a unitaryintegrated top assembly connected to the upper opening of the bladder inan air-tight manner; the top assembly including a lateral shelf, asealed body having an interior open volume and attachment componentspositioned on the body for use in connecting the top assembly to themain frame; wherein during use, pressurized air in the bladder and topassembly internal volume absorb loads applied to the vehicle.
 2. The airspring according to claim 1, wherein the top assembly body furtherincludes a connection port adapted for pneumatic communication withother air springs.
 3. The air spring according to claim 2, wherein thetop assembly body is generally formed in the shape of a half cone with acurved surface and an upright surface and the connection port is formedas a rigid arm extending from the body upright surface.
 4. The airspring according to claim 2, wherein the vehicle includes an air rideheight system connected with the pressurized air supply source, and theconnection port includes a fill port adapted for pneumatic communicationwith the ride height system.
 5. The air spring according to claim 1,wherein the top assembly body is generally formed in the shape of a halfcone with a curved surface and an upright surface.
 6. The air springaccording to claim 6, wherein the attachment components are lateral armsextending from the sides of the upright surface.
 7. The air springaccording to claim 6, wherein the lateral arms include threaded holes toengage threaded fasteners.
 8. The air spring according to claim 6,wherein the lateral arms include through holes to engage fasteners. 9.The air spring according to claim 1, wherein the top assembly bodyincludes a number of internal support ribs.
 10. The air spring accordingto claim 9, wherein the top assembly is formed from at least one of aplastic and a composite material.
 11. The air spring according to claim9, wherein the internal support ribs are upright walls oriented front toback and in parallel relation to one another.
 12. The air springaccording to claim 1, wherein the air spring is formed to maintain aninternal pressure in the range of about 15 psi to about 150 psi.
 13. Theair spring according to claim 1, wherein the air spring is formed tomaintain an internal pressure equal to or greater than about 150 psi.14. The air-spring according to claim 1, wherein the top assembly isformed from an injection molded plastic or resin composite.
 15. The airspring according to claim 1, wherein the top assembly is formed from ametal casting.
 16. An air spring for use in a motor vehicle having amain frame, a suspension system, a pressurized air supply source, and aride height system, the air spring comprising: (a) a generallycylindrical flexible air bladder having a circular upper opening; (b) asupport unit including a piston sealingly connected to the flexible airbladder, the unit further including an installation fastener rotatablyconnected through the piston and extending a distance therefrom belowthe support unit adapted to connect to the vehicle suspension system;and (c) a unitary integrated top assembly connected to the bladder upperopening in an air-tight manner; the top assembly being aninjection-molded plastic component and including a sealed body formed inthe shape of a half cone with a curved surface and an upright surface,the half cone portion of the body defining an interior open volume andincluding a number of internal support ribs; the top assembly furtherincluding a lateral shelf extending from the base of the half coneperpendicular to the upright surface; the top assembly further includingattachment components positioned on the body and adapted to connect thetop assembly to the vehicle main frame; the attachment components beinglateral arms extending from the sealed body; the top assembly furtherincluding a connection port adapted for pneumatic intercommunicationwith other air springs; the connection port including a fill portconnectable to the vehicle ride height system to allow air shuttling toand from the air springs during use.
 17. An air spring for use in amotor vehicle having a main frame, a suspension system, a pressurizedair supply source, and a ride height system, the air spring comprising:(a) a generally cylindrical flexible air bladder having a circular upperopening; (b) a support unit including a piston sealingly connected tothe flexible air bladder, the unit further including an installationfastener rotatably connected through the piston and extending a distancetherefrom below the support unit adapted to connect to the vehiclesuspension system; and (c) a unitary integrated top assembly connectedto the bladder upper opening in an air-tight manner; the top assemblybeing formed from a metal material and including a sealed body formed inthe shape of a half cone with a curved surface and an upright surface,the half cone portion of the body defining an interior open volume; thetop assembly further including a lateral shelf extending from the baseof the half cone perpendicular to the upright surface; the top assemblyfurther including attachment components positioned on the body andadapted to connect the top assembly to the vehicle main frame; theattachment components being lateral arms extending from the sealed body;the top assembly further including a connection port adapted forpneumatic intercommunication with other air springs; the connection portincluding a fill port connectable to the vehicle ride height system toallow air shuttling to and from the air springs during use.